Blog
Long-form posts on date math edge cases, business-day counting, and timezone gotchas. New post every two weeks.
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Why daylight saving time silently corrupts your date math (and the one-line fix)
DST transitions take an hour out of November and add one in March. If you do day-count arithmetic in local time, you'll be off by ±1 day twice a year. Here's why and how to fix it.
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Inclusive or exclusive? The off-by-one in date counting that costs people money
Vacation accruals, free-trial periods, prison sentences, lease terms. The same 'X days' means different counts depending on the contract — and the bug is usually in software that picks the wrong one.